63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
package compiler
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type varScope struct {
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localsCnt int
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argCnt int
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arguments map[string]int
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locals []map[string]int
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}
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func newVarScope() varScope {
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return varScope{
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arguments: make(map[string]int),
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}
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}
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func (c *varScope) newScope() {
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c.locals = append(c.locals, map[string]int{})
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}
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func (c *varScope) dropScope() {
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c.locals = c.locals[:len(c.locals)-1]
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}
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func (c *varScope) getVarIndex(name string) (varType, int) {
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for i := len(c.locals) - 1; i >= 0; i-- {
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if i, ok := c.locals[i][name]; ok {
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return varLocal, i
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}
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}
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if i, ok := c.arguments[name]; ok {
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return varArgument, i
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}
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return 0, -1
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}
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// newVariable creates a new local variable or argument in the scope of the function.
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func (c *varScope) newVariable(t varType, name string) int {
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var n int
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switch t {
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case varLocal:
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return c.newLocal(name)
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case varArgument:
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_, ok := c.arguments[name]
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if ok {
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panic("argument is already allocated")
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}
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n = len(c.arguments)
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c.arguments[name] = n
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default:
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panic("invalid type")
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}
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return n
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}
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// newLocal creates a new local variable in the current scope.
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func (c *varScope) newLocal(name string) int {
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idx := len(c.locals) - 1
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m := c.locals[idx]
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m[name] = c.localsCnt
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c.localsCnt++
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c.locals[idx] = m
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return c.localsCnt - 1
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}
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